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/* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include "libavutil/avassert.h" |
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#include "libavutil/mathematics.h" |
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#include "libavutil/attributes.h" |
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#include "kbdwin.h" |
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#define BESSEL_I0_ITER 50 // default: 50 iterations of Bessel I0 approximation |
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av_cold void ff_kbd_window_init(float *window, float alpha, int n) |
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{ |
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int i, j; |
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double sum = 0.0, bessel, tmp; |
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double local_window[FF_KBD_WINDOW_MAX]; |
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double alpha2 = (alpha * M_PI / n) * (alpha * M_PI / n); |
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✗✓ |
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av_assert0(n <= FF_KBD_WINDOW_MAX); |
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✓✓ |
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for (i = 0; i < n; i++) { |
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tmp = i * (n - i) * alpha2; |
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bessel = 1.0; |
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✓✓ |
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for (j = BESSEL_I0_ITER; j > 0; j--) |
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bessel = bessel * tmp / (j * j) + 1; |
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sum += bessel; |
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local_window[i] = sum; |
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} |
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sum++; |
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✓✓ |
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for (i = 0; i < n; i++) |
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window[i] = sqrt(local_window[i] / sum); |
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} |
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av_cold void ff_kbd_window_init_fixed(int32_t *window, float alpha, int n) |
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{ |
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int i; |
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float local_window[FF_KBD_WINDOW_MAX]; |
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ff_kbd_window_init(local_window, alpha, n); |
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✓✓ |
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for (i = 0; i < n; i++) |
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window[i] = (int)floor(2147483647.0 * local_window[i] + 0.5); |
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} |